Currently, MP3 players, smartphones, and other personal media devices are capable of storing songs and other media, processing those media, and generating audio signals for playing those media to a listener. When these devices are coupled to headphones, users, who have access to volume controls for these devices, might set the volume too high, with the effect that the sound pressure level coupled by the headphone speakers to the listener's ear(s) might cause possible hearing damage or hearing loss.
One method of limiting sound pressure level for headphones is to force the user to maintain only low-volume listening, for example by using low sensitivity headphones. While this method generally achieves the purpose of limiting sound pressure level to prevent hearing damage, it has the drawback that the full audio range of the headphone speaker is not available to the user.
Another method of limiting sound pressure level for headphones is to restrict the maximum volume presented by the headphone, even if the normal dynamics of music or other audio selected by the user would exceed that maximum volume. While this method generally achieves the purpose of limiting sound pressure level to prevent hearing damage, it has the drawback that the user can perceive significant distortion in the music or other audio selected by the user.
Moreover, modifying headphones to limit the emitted sound pressure level poses an engineering problem. First, modified headphones would then include circuitry which can be relatively costly. Second, modified headphones would then include circuitry which duplicates functions already available at the personal media device.